Fig. 4. Scatter plots and bar graph with arithmetic means ± SEM showing annexin-PE binding to O RBCs and effect of anti-C8 and anti-C9. Compared to negative control (A), phosphatidylserin (PS) exposure was significantly (p<0.001) increased after incubation with fresh serum from patients with cold AIHA (B). Pre-treatment of patient serum with anti-C8 significantly (p<0.01) reduced PS exposure (C) but RBCs still had a significantly (p<0.05) higher level of eryptotic cells compared to negative control. Pre-treatment with anti-C9 further significantly (p<0.001) increased PS exposure (D) compared to untreated patient serum. (***) p<0.001, (**) p<0.01, (*) p<0.05 compared to negative control or between the bracketed bars, respectively.